Method and apparatus for measuring belts



4 Sheets-Sheet 1 INVENTORS S. M. MARCO ETAL ATTORNEY SALVATORE M.MARCOWALLACE H.WQODROW q 4 o 3 6 8 8 w 6O B 4 6 B 2 H 2 w; 7 4% r 4 6 6 l vl/v.. 8 m// J 3 w we ?I h v k W 35 0297 32 o 5 3 32 7 O 5 w l 5 5 H Oct.13,.1964

METHOD AND APPARATUS FOR MEASURING BELTS Filed Jan. 5, 1960 6, v@@@m@0@@@w@m w%@ T Oct. 13, 1964 s. M. MARCO ETAL METHOD AND APPARATUSFOR MEASURING BELTS 4 Sheets-Sheet 2 Filed Jan. 5, 1960 W moo ms W MDmMm Y E MW. N E w 0% T T T V LL AAY SW M w m 2 b F W 1964 s. M. MARCOETAL 3,152,402

METHOD AND APPARATUS FOR MEASURING BELTS Filed Jan. 5, 1960 4Sheets-Sheet 3 INVENTORS SALVATORE M.MARCO WALLACE H.WOODROW ATTOR NEYOct. 13; 1964 s. M. MARCO ETAL METHOD AND APPARATUS FOR MEASURING BELTS4 Sheets-Sheet 4 Filed Jan. 5, 1960 INVENTORS SALVATORE M.MARCOMIISQLLACE H.WOODROW ATTORNEY United States Patent 3,152,402 NETHUD ANDAPPARATUS FOR WASURING BELTS Salvatore P/i. It'iarco, Columbus, andW'allace H. Woodrow, Dayton, Ghio, assignors to Dayco Corporation, a

corporation of Ghio Filed .ian. 5, 1960, Ser. No. 549 6 Claims. (Cl.33-147) This invention relates to the art of belt measurement, and isparticularly directed to a method and means for determining andcomparing the operative length and hop characteristics of powertransmission belts and the like.

Prior methods and equipment for belt measurement have not kept pace withthe requirements of industry, as they normally consist of mechanicaldevices for checking belts which entail long mechanical linkages andheavy moving parts through which belt measurements are transmitted to amechanical indicator. Belt measurements so obtained are influenced bybacklash and inertia effects inherent in operation of such linkages andmovement of these heavy parts, and thus their accuracy is highlyquestionable. Today, industry requires that power transmission beltshave precision characteristics so that the efficiency and output ofpowered equipment in which they are employed can be accuratelypredicted. Therefore, it is obvious that prior methods and apparatus forbelt measurement and inspection are no longer satisfactory.

The invention is directed to satisfying the needs of present dayindustry for precision methods and apparatus for checking, inspectingand comparing characteristics of power transmission belts and the like.It provides a simplified apparatus and procedure for checking theoperative length and hop characteristics of belts producing resultsaccurate to .001 of an inch by utilizing a simple but highly accurateoptical indicating means from which belt length and hop in operation canbe quickly and directly observed and compared.

A primary object of the invention is to provide improved apparatus formeasuring characteristics of transmission type belts which may be simplyfabricated and operated with a minimum of trouble and capable ofchecking a wide range of sizes and styles.

A further object of the invention is to provide a simple method fordetermining the operative length and hop characteristics of transmissiontype belts with a high degree of efiiciency and accuracy.

Another object or" the invention is to provide apparatus for accuratelymeasuring and comparing the operative length and hop characteristics ofpower transmission belts and the like.

An additional object of the invention is to provide belt inspectionequipment employing optical indicating means permitting precisionmeasurements of belt characteristics.

Another object of the invention is to provide improved means and methodsparticularly applicable for checking the operative length and hopcharacteristics of transmission type belts employing the advantageousstructural features, the inherent meritorious characteristics and themeans and mode of operation herein described.

With the above primary and other incidental objects in view which willmore fully appear in the specification, the invention in ended to beprotected by Letters Patent core sists of the features of construction,the parts and combination thereof, and the mode of operation hereinafterdescribed or illustrated in the accompanying drawings, or theirequivalents.

The drawings illustrate a preferred form of the invention, in which:

FIGURE 1 is a front elevation of the apparatus, partially in section, inaccordance with the invention;

FIGURE 2 is a side view of the apparatus of FIGURE 1, with portions ofthe structure broken away for clarity;

FIGURE 3 is a view of a portion of the apparatus, taken along lines 33of FIGURE 2;

FIGURE 4 is a sectional view of the lower sheave support, taken on lines44 of FIGURE 1;

FIGURE 5 is a sectional view of the optical reflector assembly takenalong line 5--5 of FIGURE 2;

FIGURE 6 is a sectional view taken on line 6-6 of FIGURE 5;

FIGURE 7 is a sectional view of the projection unit taken along line 77of FIGURE 1; and

FIGURE 8 is a view, partially in section, taken along line 3 8 of FIGURE1.

Turning now to the drawings, the novel device is housed in a framework11 consisting of a number of structural beams which may be bolted,welded, or riveted together. As best shown in FIGURES 1 and 2, theframework is essentially rectangular and includes a pair of verticalbeams 12, interconnected at top and bottom by cross beams 13, formingthe front of the framework. A similar set of vertical beams 14 areinterconnected by cross beams 15 at top and bottom and form the rear ofthe framework. The front and rear sections are interconnected by meansof four transverse beams 16, which run from the corners of each of theintersections of vertical and cross beams. These members thus form theopen rectangular framework 11 which is the primary structure. For addedstrength, a pair of intermediate vertical beams 17, located betweenfront and rear vertical beams 12 and 14, extend between upper and lowertransverse beams 16.

Mounted on the rear face of and inward of the front vertical beams 12 bymeans of bolts 51, are plates 18 and 1?, having apertures 2i) therein.These apertures are very accurately spaced and located, for example,exactly one inch apart, in order to provide incremental mounting ofcross members as described below. Mounted on the forward face ofintermediate vertical members 17 are similar plates 21 and 22, invertical and horizontal alignment wi h plates 13 and w respectively.These latter plates also have apertures 24 which align with theapertures in the forward plates. The plates 18 and 21 on the left sideof the framework extend somewhat higher than plates 19 and 22 on theright side.

A support 23 extends horizontally across the front portion of theframework 11 spaced above and generally parallel to the cross beam 13,and is mounted between plates 18 and 21 at one end and plates 19 and 22at the other end. This support 2-3 may have any cross-section, but isshown as a U-shaped channel member. The ends of the support are providedwith axially aligned apertures adapted to align with apertures in theconfining plates, and are mounted thereto by means of bolts 24 whichpass through the aligned apertures to fix the position of the supportrelative to the framework 11. A threaded bolt 25 is engaged through anaperture in the horizontal portion of the support 23, the head of thebolt 25 abuttmg the undersurface of the support and its threadedextremity projecting vertically to receive a nut 26 thereabout whichclamps the bolt to the beam. A rectangular cup-like housing member 27has the center of its base seated on the end of bolt 25 to define thelowermost position of member 27. The upper end of the member 27 has anexternal flange 28 which is mounted to another portion of the structureas later described. A coil spring 29 is mounted within member 27, andmounted on the upper end of said spring, and concentrically containedwithin the member 27, is a housing 29a which provides a bearing for ashaft 3%. (See FIGURE 4.) The ends of the shaft 30 project from, and atright angles to, the forward and rear faces of the housing 29a, spacedvertically upward from the upper extremity of the cup-like member 27.Upon the end of the shaft 39 which projects from the forward face of thehousing is mounted a pulley 36a.

Fixed to the upper surface of support 23 is a support bracket 31 whichprojects rearwardly from the support to mount a motor 32. The motor 32is so positioned that its drive shaft projects at right angles to shaft39 and is spaced below and to the rear thereof. A transmission .unit 33is mounted on the motor 32 to connect to the motor drive shaft andprovide an output shaft 34 arranged parallel to and below the shaft 30.Conventional drive gears 35 and 35a are mounted on these shafts andprovide a positive drive to shaft 30 and therefore, to pulley 30a.Conventional controls are provided to energize the motor 32 to drive itsshaft through transmission unit 33.

A structural supporting beam 36 preferably having a V-shaped section,extends horizontally across the front of the framework above andparallel to the support 23, and is mounted near its left end betweenplates 18 and 21 by means of a bolt 37 which provides a pivotal supportthrough the beam and aligned apertures of the plates. The left end. ofthe beam projects outwardly of the frame work 11 between the plates, andon the cantilevered end thereof is mounted an air cylinder 38. The otherend of beam 36 extends across the framework from the pivot 37 toterminate between the plates 19 and 22. The beam 36 also provides amounting on its lower surface for the cup-like housing member 27 whichis attached thereto by means of bolts 39 passing through flange 28. Thebeam is cut away to provide for the mounting of the housing 29a referredto above, as shown in FIGURE 1.

Also mounted on the beam 36, at the upper surface of the right hand endthereof, is a bracket 40. The bracket includes a downwardly extendingarm 41, which has an aperture extending therethrough, larger in diameterat the right end of the arm to provide a spring retaining recess 42. 7

An externally threaded shaft 43 extends through the aperture, and aconical collar 44 is mounted on the shaft as shown in FIGURE 1. A coilspring 45 is mounted concentrically of the shaft 43 and retained at oneend by the shoulder in recess 42, and retained at the other end by awasher 46 about the outwardly projected end of shaft 43. The washer isclamped to the outer face of arm 41 by means of a nut 47 which ismounted on the end of shaft 43 outwardly of the washer.

The major portion of shaft 43 projects inwardly of the framework 11 andis mounted in a cam plate 48 which in elevation has the general form ofa right triangle. Shaft 43 enters the right side of cam plate and runsparallel to its upper surface, which is parallel to the member 36. Thelower surface 49 of the cam plate slopes upwardly to the left.

The housing 29a, Which is directly in the path of plate 48, has atransverse groove in its upper surface and the innermost extremity ofplate 48 is slidable therein as shown in FIGURE 4. The spring 45produces a bias against bracket which is directed outwardly of theframework. By rotation of nut 47 which is locked on shaft 43, the shaft43 is also rotated and drives cam plate 48 to the left or to the right,which in turn moves housing 29a to create a fine vertical adjustment ofhousing 29a and pulley 30a thereby, either under or against theinfluence of spring 29 which reacts against the housing. A longitudinalarm 50 is mounted to project outwardly at right angles to the outermostface of arm 41 parallel to shaft 43 and adjacent the outer peripheralportion of collar 44. The collar 44 and arm 50 are appropriately scaledto cooperate and provide a precise reading off any Vernier type verticaladjustment of pulley 36a for purposes to be further described.

It will be seen at this point that beam 36 is connected at one end offramework 11 at a single pivot by bolt 37 while its other end is freelysupported on housing 29a through the medium of cam plate 48 hearing inthe groove of said housing. A hearing plate 52 is fixed to the uppersurface of beam 36 to extend from a point outwardly of pivot 37 betweenplates 18 and 21 to a point inwardly of the framework 11 to the otherside of bolt 37. Plate 52 has a guide channel longitudinally of itsupper surface slidably accommodating a cam plate 53, the upper surfaceof which is inclined downwardly to the right as shown in FIGURE 1. Apiston rod 54 projecting from the air cylinder 38 connects to plate 53for movement longitudinally of the plate 52, for reasons to be explainedbelow. A pair of brackets 55 are attached to the plates 18 and 21 bymeans of a bolt 56. At the other'end of these brackets 55 is a roller 57which is mounted on a rotatable shaft 57a attached to the brackets. Theroller bears upon the inclined upper surface of plate 53.

Mounted on the upper surface of the upper cross beam 13 are a pair ofbrackets 58, mounted at the forward side, and a pair of brackets 59,mounted on the rearward side of the framework. A pulley 66 is mountedwithin brackets 58, and a similar pulley 61 is mounted within brackets59, both pulleys in horizontal alignment. A cable 62 extends acrosspulleys and 61 and passes downward in the front of the framework toconnect to the eye 63 of a rod mounting a suspension unit 64. To thelower extremity of unit 64 is mounted a plate 65 bolted to the uppersurface of a housing 66 which serves as a bearing means rotatablymounting a shaft 67. Mounted on the forward face of shaft 67 is a pulley68 which is in the same plane as pulley 30a. The other end of cable 62extends around the back of framework 11 to connect to a shackle 69pivotally fastened by bolt 70 to a bar 71 adjacent and spaced from oneend thereof, as best shown in FIGURES 2 and 3. The bar 71 is pivoted atthis one end to a vertical beam 14 of framework 11 at pivot point 71a,while its other end extends across the back of the framework andprojects through a vertical slot in a bracket 72 fixed to the other beam14. Fixed to the end of bar 71 and forming an axial extension thereofoutwardly of the framework 11 is an externally threaded rod 73. A seriesof annular weights 74 mount on rod extension 73 between nuts 75 and 75a,and provide a counterweight for applying a predetermined tension oncable 72 through bar 71 to exert a bias on sheave 68, causing it toassume a particular reference position vertically of framework 11governed by the nature of suspension unit 64.

Mounted on the right hand side of the framework 11 is a housing 76, moreclearly detailed in FIGURE 5. The housing 76 has a right hand face 77and a left hand face 78, and an axial opening 79 extending between thesefaces. Mounted within the opening 79 is a tubular sleeve 80 which isrotatably mounted in the housing 76. One end of this sleeve has a flange81 abutting a mating shoulder 82 on the housing, while the other endprojects outwardly from the face 77. The outwardly projecting end ofsleeve 80 has a cut out portion from a point spaced outwardly of thehousing face 77 leaving a projecting extremity 83 which is arcuate andless than semi-circular in cross-section. On the projecting extremity 83is mounted a mirror 84, the uppermost surface of which forms a part ofthe periphery of the extremity. The mirror 84 is uppermost and spacedoutwardly from the extremity of the cut back portion of sleeve 80 whichis provided with a central notch 85, at right angles to the mirror 84. Acentral shaft 86 is rotatably mounted within the sleeve 80, and isconcentric therewith. The shaft 86 has a radially enlarged portion 87which abuts flange 81 to provide thrust bearing, and a ring 83 ismounted concentrically of the shaft portion 557 by means of a set screw87a. A pair of abutting axially aligned ball bearings 89 are mountedabout shaft 8-6 between the ring 88 and a similar ring 91) which ismounted at the end of the shaft. The bearings thus permit relativerotation of the shaft 86 and the outer tubular sleeve Another ring 91,spaced outwardly of ring 9t, is fixed concentric therewith by means of aset screw 92 to abut the outer race of the bearings. The left hand endof shaft $6 is threaded and projects from the housing face 78 to mount acollar 920 which is integral with control arm )3 in spaced relationthereto confined between ring 9% and nut 93a. The arm 93 extends atright angles to the shaft 36 in a horizontal plane.

The end of shaft 56 projecting from the housing at its face 77terminates just short of the mirror 34 mounted on the outer sleeve 31?,and is cut back in a similar manner LO extremity 83 to permit mountingof mirror 94 on its uppermost surface. This mirror 4 forms the upperperiphery of the shaft. Both mirrors 34 and 94 are thus adjacent andextend outwardly of the housing 76 and the framework ii, at the rightside as viewed in FIG RE 1. As best shown in FIG- URE 6, a pin 95 isprojected through shaft 86 to have one end project through the notch 85in sleeve A collar 96 is mounted about the notched portion of sleeve 89adjacent the face 77 of housing 76. The collar 96 has a portion 97 whichis located radially outward from sleeve 8%) opposite notch S to provideparallel arms 98 at either side of the notch and either side of pin 95.Set screws 99 adjustably engaged through arms 98 at either side of pin95 provide means for limiting the movement of pin $5 relative the sleeve2%), and thus will also limit movement of the inner shaft 35 withrespect to sleeve 8%). This will be more fully described below. It willbe noted that sleeve 84 is rotatable relative to the housing 76. Thehousing 76 is provided with opposed apertures communicating with sleeveSt) at diametrically opposed positions. Friction members 169 are mountedWithin the housing 75 to frictionally engage sleeve 3%? and are held infrictional engagement therewith by means of set screws Mil. The sleeve89 is therefore rotatable, yet may be held in any position to which itis turned, by friction members 13%). As shown in FIGURE 8, arm 93 ispositioned by a spring 183 which is attached to the framework 11 bymeans of a pin 133.4. The other end of the spring is connected to a lug1%. which passes through the arm 93 and is held thereto by means of setscrew 192a. This assembly thus establishes an adjustable bias on the arm93. The arm is established in a predetermined position to normallyorient mirror 9 to zero with mirror 84.

Mounted on housing 66 is an arm 113 which is at right angles thereto asseen in FIGURE 1. This arm rests upon arm 93 (see FIGURE 8) to maintaina predetermined relationship between the mirrors and the pulley 68(through housing 66). This relationship also permits movements of pulley63 to be transmitted through arms 118 and 92 to the mirrors.

A support plate 164 is bolted at one end to the right side of framework11 at the rear beam 14, and projects rearwardly of the framework. Aplate 1 35 is fixed to project outwardly at right angles to plate 134and forms an arc to present a concave screen in the path of mirrors 84and 94. As shown in FIGURE 1, this screen is indexed to providereference positions as described below.

A lamp assembly 1% is mounted on the right side of the framework bymeans of a bracket 1317 having a right angled support arm adjustablymounted on upper beam 16. As shown in FIGURE 7, assembly iiiincludes alamp housing 103 having fins to dissipate heat radiating from a pair oflamps therein. The housing has a central adapter 1%? bolted about anaperture, and has a pair of parallel apertures therethrough fordirecting the beams from the lamps to the mirrors 8% and 94. The

surface of the adapter 199 adjacent housing 108 is countersunk at theapertures to nest plates 110 having narrow rectangular slits 111 thereinfor narrowing the projected lamp beams. adapter 169, oriented to disposeknife edge extremities thereof over opposite ends of slits 111, arepairs of opposite blade elements 112 having right angled portions 113extending away from adapter 199. Screws 114 are projected through theright angled portions 113 of blade elements 112 to engage the adapter.By rotation of the screws 114 the respective pairs of blade elements 112may be adjusted relative to the slits 111 to vary the area for passageof light beams therethrough in accordance with the requirements of the aparatus. A housing 115 mounting over the projected face of adapter 1&9has apertures aligning within the apertures therein and adapters 116forming projections thereof mounting lens elements 117. The bracket 1T1may be adjusted to insure that the light beams projected from the lampassembly 106 will impinge upon the mirrors 84 and 94 so that the lightbeams will be reflected from the mirrors to project upon screen inaccordance with the respective positions of the mirrors.

Operation of the Apparatus As indicated previously, the apparatusdescribed above is used for measuring the length of belts in order tocompare them with standard, or ideal lengths; and is also used formeasuring belt hop, or variation in length. When it has been establishedthat a certain length of belt is to be measured, the beam 23 is mountedon the framework 11 by means of bolts 24 through apertures 21? in platesl3, 3.9, 21, and 22. The specific apertures selected will be governed bythe aforesaid belt length, since these apertures are spaced apart atexact dimensions, preferably one inch. Thus the relationship betweenbeam 23 and beam 36 is determined, with the beam 36 in a horizontalposition as shown in FIGURE 1. The beam 36 is locked in this position byvirtue of the fact that cam plate 53 is locked under the roller 57 whichis mounted on the framework. The lowermost position of the beam 36 iscontrolled by setting the bolt 25, upon which the bottom of member 27rests. Since member 27 is attached to beam 36, the bolt 25 thus servesas a bottoming control which is set once and not changed during theinspection.

The upper pulley 63 is now established at a position necessary toprovide the exact distance between it and the lower pulley 30a which hasbeen located by the positioning of the two beams. It is possible thatthe distance between Ella and 68 corresponding to the required beltlength cannot be established exactly by the above procedure. in such acase, further adjustment of the pulley Ella may be accomplished by aVernier system which is capable of producing any desired spacing, to anaccuracy of .001 inch, between the one inch spacing determined by beamlocation. This fine adjustment is accomplished by rotation of the nut 47which is fixed on shaft 43, rotating this shaft and collar 44- to movecam plate 48 inwardly or outwardly from the groove in housing 27. Asseen in FIGURE 4, motion of the cam plate will urge pulley housing 29::downward against bias of spring 29. It should also be noted that thespring 29 has another function in the system, in that it acts as adampener to eliminate backlash. The amount of vertical adjustment isdirectly ascertained in a conventional manner from the resultingrelationship of the markings on collar 44 and the adjacent arm 5%. Theoperating arm 118 projecting from the upper support housing 66 is now ina zero reference position and bears on control arm 93 to position shaft86 and connected mirror 94 is a zero reference position which should bethe design or standard belt length.

/hen it is desired to check the length or hop of a series of beltsfalling within the group having the predetermined length, the apparatusmust first be arranged to permit mounting a belt. This is accomplished'by actuating Also confined between housing 108 and cylinder 38 to drivethe piston rod 54 to the left, thus also driving the cam plate 53 to theleft (as shown in FIGURE 1). This releases the locking interengagernentwith the roller 57, which permits the beam 36 to be free to pivot aboutbolt 37. Because of the weight of the cylinder 38 which is mounted onthe end of the beam, this beam is rotated counterclockwise, raisingpulley 3&1 upward sufficiently so that belt B can be positioned overthis pulley and pulley 68.

The air cylinder 38 is next actuated again to reverse the movement ofpiston rod 54 to the right, thus once again locking cam plate 53 underroller 57, and thus seating the beam 36, pulley 30a and member 27against the bolt 25. At the same time the gear 35a is dropped into meshwith gear 35 so that the mechanism shown in FIGURE 4 can be operatedwhen motor 32 is turned on. A switch is actuated to supply power to lampassembly 106, and the projected light beam (indicated by dotted lines inFIGURE 2) is reflected from the outer, or relatively fixed mirror 84 andonto the curved screen 1%5. If the belt is approximately of the correctlength, this light beam will fall in the center of the screen. The motor32 is next actuated, causing pulley 36a to drive belt B and pulley 68through shaft 34, gears 35 and 35a, and shaft 30. During this operation,the minimum length of the belt will, of course, be measurable; at suchlength the upper pulley will be at its closest point to the lower pulley(lowermost position), and the housing 66 and arm 118 Will also reachtheir lowermost position. Arm 118 will, in turn, pull the arm 93downward, rotating this arm and shaft 86 in a clockwise direction (asviewed in FIG- URE 8). This in turn causes the pin 95, which is fixed tothe shaft 86, to rotate and strike against the right hand set screw 99(FIGURE 6), and this successively drives collar 96, sleeve 80, andmirror 84 to the right, thus refleeting the light beam to a point on thescreen which represents the minimum belt length. This point, of course,is the lowermost point of reflection on the screen. The friction members100 will now tend to keep the sleeve in this position during theoperation of the pulleys and belt. The operator may now read this pointon the screen as the actual belt length in order to determine whether itfalls within the required range of lengths.

In addition to providing the nominal belt dimension, the operation ofthe belt and pulleys simultaneously indicates the variation in length,or hop. This is accomplished by the vertical motion of the belt, whichin turn moves pulley 68 up and down against (or under) the influence ofthe counterweight system. At the same time the arm 118 is reciprocating,and the arm 93 is oscillating under influence of arm 118 or spring 103,and this oscillation is transmitted to shaft 86 and then to the innermirror 94 mounted thereon. The screws 99 have previously been set sothat the oscillating pin 95 (moving with shaft 86) will not reach thesescrews, and thus the minimum length previously established will not bedisturbed. The amount of oscillation of the mirror 94 will govern therange of reflection of light from its source and will appear on thescreen as a beam of light oscillating upward from the previouslydetermined minimum point up to a maximum and back again. The screen hasa radius in the order of 25 inches, which provides highly accuratereadings because of the great magnifications of the comparatively smalloscillation of the mirror, which in turn is a function of the distancebetween the shaft 36 and the point where arm 118 contacts arm 93.

Thus, the method and apparatus of the invention has been shown to besimple and versatile. Since there are a great many applications of theinvention its use is presented only in illustrative fashion andvariations may be effected to meet the requirements of a particularsituation. These will be obvious to those versed in the art, and,accordingly, need not be exhaustively presented. The machine providedwill accommodate many lengths and varieties of belts with the sameaccurate results. The

provision for Vernier adjustment of pulley 30a gives the apparatus anextreme flexibility and permits precision inspection and checking to adegree not heretofore contemplated. The use of accurately and preciselyreferenced mirrors to reflect belt length and hop characteristics avoidsneed for complex recording mechanisms. The magnification or" reflectedbelt characteristics provided by the nature and disposition of screenfacilitates precise measurement of the noted belt characteristics to atleast Within .091 of an inch.

From the above description will be apparent that there is provided adevice of the character described possessing the particular featuresenumerated as desirable, but which obviously is susceptible ofmodification in form, proportion, detail construction and arrangement ofparts without department from the principles involved or sacrificing anyof their advantages.

We claim:

1. Apparatus for measuring belts including a fixed and an adjustablepulley in spaced relation, means for establishing reference positionsfor said pulleys in accordance with the desired length of a belt to bemeasured, a screen, a first reflecting means operatively connected tosaid adjustable pulley and movable therewith to reflect variations inits position, said first reflecting means having a light sourceassociated therewith for projecting on said screen a visual indicationof the movements of the adjustable pulley to accommodate said belt, anda second reflecting means operatively connected to said first reflectingmeans oriented to project a visual indication on said screencorresponding to the desired belt length.

2. Apparatus for measuring belts including a fixed and a relativelymovable pulley for mounting a belt of a desired size, a concave screen,means for transmitting a light impression on said screen indicative ofthe position of the relatively movable pulley, means for driving saidpulleys and said belt, and further light transmitting means operativelyconnected to said movable pulley for transmitting belt length and hop inthe form of a light beam projected on said screen.

3. Apparatus for measuring belts including a pair of pulleys, one fixedand the other under bias to establish a predetermined reference spacingtherebetween accommodating a belt of specified length, a pair of mirrordevices axially aligned and operatively connected for establishing oneof said mirror devices in a reference position, means operativelyconnecting said other mirror device for movement under the influence ofmovement of one of said pulleys, a light source directed to saidmirrors, and a concave screen in the path of said mirrors to receivelight beams reflected therefrom which are indicative of length of thebelt on the pulleys as compared to the specified length.

4. A method of measuring a transmission belt includ ing the steps ofestablishing a pair of relatively biased pulleys in predetermined spacedrelation corresponding to a required belt length, applying a belt to bemeasured to said pulleys, optically transmitting a visual impression ona screen corresponding to the required belt length, and opticallytransmitting to said screen a magnified visual impression of pulleyadjustment to accommodate the actual length of the belt and provide adirect representation of actual belt length thereon as related torequired belt length.

5. A method of checking a belt for length and hop during operationincluding the steps of establishing a beam of light on a screen relatedto the required pulley spacing for a specific length belt, driving saidbelt about relatively biased pulleys referenced to said screen toprovide for relative automatic adjustment of said pulleys to accommodatethe actual length of the belt, optically magnifying the relativeadjustment of said pulleys and projecting a comparative beam on saidscreen to show precise deviation of the actual from the required beltlength and variation in pulley spacing resulting from belt hop inoperation.

6. A method of checking the length of a belt including the steps ofestablishing belt mounting means in spaced relation, to provide formounting a belt of a desired length, projecting a light beam on a screenreferenced to said mounting means at a position indicative of thedesired 5 belt length, applying a belt to be checked to said beltmounting means, optically magnifying relative adjustment of the beltmounting means to accommodate the belt and projecting a light beamcorresponding thereto on said screen to provide a precise opticalcomparison of the 10 actual length of said belt to said desired length.

References Cited in the file of this patent UNITED STATES PATENTS EdisonOct. 14, 1890 Thearle Feb. 13, 1934 Gates Apr. 17, 1934 Hedgepeth June23, 1936 Furst May 30, 1939 Schick et a1. May 4, 1943 Haren Dec. 5, 1950Freeder June 17, 1958

1. APPARATUS FOR MEASURING BELTS INCLUDING A FIXED AND AN ADJUSTABLEPULLEY IN SPACED RELATION, MEANS FOR ESTABLISHING REFERENCE POSITIONSFOR SAID PULLEYS IN ACCORDANCE WITH THE DESIRED LENGTH OF A BELT TO BEMEASURED, A SCREEN, A FIRST REFLECTING MEANS OPERATIVELY CONNECTED TOSAID ADJUSTABLE PULLEY AND MOVABLE THEREWITH TO REFLECT VARIATIONS INITS POSITION, SAID FIRST REFLECTING MEANS HAVING A LIGHT